X-ray intensifying screen



Nov. 9, 1954 F. w. REUTER 2,694,153

X-RAY INTENSIFYING SCREEN I Filed Aug. 3, 1950 2' FLUORESCENT COA TING I MAGNETIZABLE METAL 2 FLUORESCENT COA TING 4 MAGNETIZABLE PARTICLES IN POLYMERIC FILM 2 FLUORESCENT COA TING l MAGNET/ZABLE METAL 2 FLUORESCENT COA TING 4IMAGNETIZABLE PARTICLES m POLYMERIC FILM .INVENTOR. E"ederic WEeaZEr BY I AT TORNEY United States PatentO This invention relates to X-ray intensifying screens.

\ More particularly it relates to such screens which pro- Still more particularly, it relates to X-ray intensifying screens which have a support or a stratum thereof responsive to a magnetic field.

X-ray intensifying screens are used "in the radiographic art to intensify the image produced in an exposed X-ray sensitive film. Since the films often have a large surface area it is difficult to obtain uniform intimate contact between the fluoroscent surface of the X- ray intensifying screen and the light-sensitive surface of the film. In order to overcome this difliculty cassettes are usually provided with felt layers. However, such layers are not very resilient and it is dificult to obtain uniform pressure throughout the area.

An object of this invention is to provide an improvement in the art of X-ray intensifying screens. A further object is to provide a simple and effective means for bringing an X-ray intensifying screen surface into intimate and uniform contact with an X-ray sensitive film element. A more specific object is to provide X-ray intensifying screens with a support or strata which responds to the effect of a magnetic field. Still other objects will be apparent from the following description of the invention.

The X-ray intensifying screens of this invention con-' rvide uniform intimate contact with X-ray sensitive films.

"used in various types of cassettes.

sist of a layer containing a material which fluoresces when excited by X-rays disposed on a snooort which is responsive to the effect of a magnetic field. The support may be composed of a single sheet of a magnetizable metal or alloy or a thin sheet laminated to a sheet of non-magnetic material which is permeable to X-rays or may be composed of or contain a stratum of finely divided particles of magnetizable material in a filmforming binding agent, e. g., cellulose derivative, resin, superpolymer, etc.

The invention will be further illustrated with reference to the accompanying drawing which constitutes a part of this specification herein. In the drawing similar reference numerals refer to similar parts throughout the several views.

Fig. 1 is a perspective view of one form of magnetic M fluorescent screen.

Fig. 2 is a perspective view of another form of magnetic fluorescent screen.

Fig. 3 is a perspective view of yet another form of ma netic fluorescent screen.

Fig. 4 is a perspective view of a still further form of magnetic fluorescent screen.

Referring now to Fig. l of the drawing a sheet of magnetizab e metal or alloy 1 which mav be composed of iron, steel, a ferrous and/or nickel alloy, an aluminum-nickel-cobalt alloy, etc., has disposed on its surface a layer 2 of fluorescent material which is excited by X- rays and emits light in the ultra-violet and/or visible and/or infra-red region of the spectrum.

In Fig. 2 which constitutes a preferred aspect of the invention a thin sheet of magnetizable metal or alloy 1 is laminated to a paper or cardboard support 3 which has disposed on its surface a layer 2 of fluorescent material. The sheet 1 can be affixed to the paper or cardboard support by means of any suitable adhesive, e. g., glue. or a resin or cellulose derivative.

Fig. 3 illustrates a still further modification of the invention. The magnetic fluorescent screen consists of a suitable support 4 which may be composed of a hard 2,694,153 Patented Nov. 9., 1954 film-forming or plastic polymeric material which has intimately dispersed therethrough particles of magnetizable materials such as finely divided particles of iron or iron oxide provided with a layer or coating 2 of a fluorescent material. The support can be made by extruding or casting a dispersion of magnetizable particles in a polymeric binding agent, for example, a cellulose derivative such as cellulose acetate, cellulose nitrate, cellulose acetate-propionate; a synthetic resin or super polymer, e. g. a polymethyl metchacrylate, phenolformaldehyde condensation product, polystyrene, polyvinyl chloride, nylon, saran, etc., from a fluid mixture or solution of the polymeric binding agent in a suitable organic solvent. The resulting sheet support or film is then provided with a layer 2 of a suitable fluorescent material which is excited by X-rays and emits light in the ultraviolet, visible or infra-red region of the spectrum.

A still further type of screen is illustrated in Fig. 4 wherein a suitable support 5 which may be composed of material permeable to X-rays, e. g., paper, cardboard, cellulose derivative, resin, superpolymer or metal, is provided with a coating or layer 4 of the same constitution as support 4 of the magnetic fluorescent screen of Fig. 3. The binding agent while preferably composed of a hydrophobic material can be composed of other materials including water-permeable colloids, gelatin, polyvinyl alcohol, hydrophilic polyvinyl acetal of formaldehyde, acetaldehyde, butyraldehyde, benzaldehyde, etc.

In all of the screens referred to above the sheet of magnetizable metal should be of sufficient thickness that it will have adequate attraction for a magnetic field and be drawn toward the field. In the case where finely divided metallic particles are used the concentration or amount of the particles should be chosen so that the film orstratum will have adequate attraction for a magnetic field and be drawn toward such field. In addition,

it should be of such thickness that it is still sufficiently permeable to X-rays to adequately expose a film element. It should be apparent from the above that the novel magnetic X-ray fluorescent intensifying screens can be The surface area of the screen, in general, should be at least as large as the utilized area of the X-ray film element and should fit loosely in the casette so that it can be drawn into uniform intimate contact with the surface of the film element by a magnet or magnetic field disposed adjacent to or near the outer surface of the cassette. In use the magnet is energized just prior to an X-ray exposure.

, The invention will be further illustrated but is not intended to be limited by the following examples.

Example I A sheet of annealed iron a proximately 0.002 inch thick was provided with an X-ray fluorescent coating comprising a nitrocellu ose dispersion of mixed crystals of lead and barium sulfate. The fluorescent surface of this magnetic screen was placed in contact with the light-sensitive surface of an X-ray fi m element in a cassette and the loaded casette was nlaced adiacent a magnet having its magnetic field spread over a large surface area c mmensurate ith the screen. The ma net was energized during an X-rav exp sure thus ulling the scre n into niform con act with he film. The resulting X-ray picture showed good unif rm c ntact bet een the fluore cent coating and the light-sensitive emulsion layer on the film.

Example II A thin sheet of annealed iron approximately 0.001 inch thick w s aflixed to the back of a conventional 'X-ray intensifving screen having a cardboard support Example III A magnetizable film base was made by casting onto a suitable smooth surface a dispersion of the following general composition:

Parts Cellulose nitrate 100 Plasticizers I 8 Methanol .292 Iron powder (average particle size 1.0 micron) 400 A magnetizable film base was made by casting onto a suitable smooth surface a dispersion of the following general composition:

Parts Cellulose nitrate 100 Plasticizers 8 Methanol 292 Magnetic gamma ferric oxide (average particle size 1.0 micron) 400 to yield a dried-film thickness of 0.01 inch. The resulting film was dried, then coated with a nitrocellulose dispersion of fluorescent calcium tungstate and stripped from the casting surface. The resulting magnetic screen was placed in a loaded cassette which was exposed after the manner described in Example I with similar results.

This invention has the advantage that it provides new X-ray intensifying screens which have considerable utility in the art and can be used in various types of X-ray cassettes. The screens give uniform and intimate contact with a light-sensitive film element when subjected to the influence of a magnetic field. The magnetic X-ray intensifying screens are simple in construction but yet effective. They can be readily used by the ordinary laboratory technician with good results. The screens have a relatively long effective life and do not require excessive care in handling.

As many widely diflerent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimed is:

1. An X-ray intensifying screen consisting of a sheet support having a stratum which is attracted by a magnetic field and is permeable to X-rays and a layer of fluorescent material which is excitable by X-rays, said layer of fluorescent material being the only layer in said screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the stratum attracted by a magnetic field nearest the source of X-rays.

2. An X-ray intensifying screen consisting of a thin ferrous metal sheet that is permeable to X-rays bearing at least one layer of fluorescent material which is excitable by X-rays, said layer of fluorescent material being the only layer in said screen that is markedly sensitive to X-rays. the said screen being adapted for insertion in a cassette with the metal sheet nearest the source of X-rays.

3. An X-ray intensifying screen consisting of a thin magnetizable metal sheet that is permeable to X-rays laminated to a support permeable to X-rays bearing at least one layer of fluorescent material which is excitable by X-rays, said layer of fluorescent material being the only layer in said screen that is markedly sensitive to X-rays, the said screen being adapted for insertion i a cassette with the metal sheet nearest the source of 1 -rays.

4. An X-ray intensifying screen consisting of a thin magnetizable metal sheet that is permeable to X-rays laminated to a cardboard support permeable to X-rays hearing at least one layer of fluorescent material which is-excitable by X-rays, said layer of fluorescent material being the only layer in said screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the metal sheet nearest the source of X-rays.

5. An X-ray intensifying screen consisting of a thin ferrous metal sheet that is permeable to X-rays laminated to a support bearing a layer of fluorescent calcium tungstate, said layer of fluorescent calcium tungstate being the only layer in the screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the metal sheet nearest the source of X-rays.

An X-ray intensifying screen consisting of a thin ferrous metal sheet that is permeable to X-rays laminated to a support bearing a layer of fluorescent mixed crystals of lead and barium sulfate, said layer of fluorescent crystals being the only layer in the screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the metal sheet nearest the source of X-rays.

7. An X-ray intensifying screen consisting of a hydrophobic polymer film having uniformly distributed therethrough finely divided particles of magnetizable material, said film being permeable to X-rays and bearing a layer of fluorescent material which is excitable by X-rays, said layer of fluorescent material being the only layer in said screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the film nearest the source of X-rays.

8. An X-ray intensifying screen consisting of an organic hydrophobic polymer film bearing a layer of an organic polymeric binding agent having uniformly distributed therethrough finely divided magnetizable particles, said layer being permeable to X-rays, and a layer of fluorescent material which is excitable by X-rays, said layer of fluorescent material being the only layer in the screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the layer of polymeric binding agent being nearest the source of X-rays.

9. An X-ray intensifying screen consisting of an organic hydrophobic polymer film bearing a layer of an organic polymeric binding agent having uniformly distributed therethrough finely divided iron particles, said layer being permeable to X-rays, and a layer of fluorescent mixed crystals of lead and barium sulfate, said layer of fluorescent mixed crystals being the only layer in the screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the layer of polymeric binding agent nearest the source of X-rays.

10. An X-ray intensifying screen consisting of an organic hydrophobic polymer film bearing a layer of an organic polymeric binding agent having uniformly distributed therethrough finely divided iron particles, said layer being permeable to X-rays, and a layer of fluorescent calcium tungstate, said layer of fluorescent calcium tunustate being the only layer in the screen that is markedly sensitive to X-rays, the said screen being adapted for insertion in a cassette with the layer of polymeric binding agent nearest the source of X-rays.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,448,456 Levy et al. Mar. 13, 1923 1,532,795 Balch Apr. 7, 1925 2.267999 Switzer Dec. 30, 1941 2,318,184 Rojas May 4, 1943 2,336,815 Tasker Dec. 14, 1943 2, 9,162 Staud Oct. 8, 1946 2,530,321 Armstrong Nov. 14, 1950 

